What absorbs at 1376 cm⁻¹ in an FTIR spectrum?
A band near 1376 cm⁻¹ can point to several functional groups. Below are the most likely assignments, ranked by how much published evidence supports each — every one traceable to literature (DOI) and cross-validated against our 130,000+ reference spectra and knowledge graph.
Backed by 8 cited sources
Quick answer
A band near 1376 cm⁻¹ is usually interpreted by checking which functional groups repeatedly co-occur there in the literature, then confirming at least one or two additional peaks in the same sample. This page ranks those assignments by accumulated evidence rather than by a single fixed textbook rule.
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Alkyl C-H | 18 | 18 | 1.0 |
| Methyl | 11 | 11 | 1.0 |
| Methoxy (OCH3) | 7 | 7 | 1.0 |
| Methacrylate | 7 | 7 | 1.0 |
| Acetate | 7 | 7 | 1.0 |
| Hydroxyl (O-H) | 5 | 5 | 1.0 |
| Amide | 4 | 4 | 1.0 |
| Alkene (C=C) | 3 | 3 | 1.0 |
| Carbohydrate | 2 | 2 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Borate | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| Amino acid | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.
Possible materials
| Material | Supporting peaks | Overlapping groups | Cited sources |
|---|---|---|---|
| nanocellulose | 1376, 1540, 1646 | Alkyl C-H, Methacrylate, Methoxy (OCH3) | 1 |
| polypyrrole | 1376, 1700, 400 | Alkyl C-H, Methacrylate | 1 |
| collagen | 1376, 1408, 1660 | Methacrylate, Alkyl C-H, Methoxy (OCH3) | 1 |
Materials are shown only when the same literature pool supports this band and at least one additional characteristic peak.
Spectrum logic
This band becomes meaningful only when read with its neighboring peaks. In practice, analysts first look at the assignments above, then check whether the same sample also shows other peaks expected for the same structural motif. A lone band near 1376 cm⁻¹ is usually not enough for material identification by itself.
Real-world usage
This type of query is common in polymer identification, unknown plastic screening, QC troubleshooting, recycled-material verification, and literature-backed peak assignment review.
Common mistakes
- Treating one isolated band as proof of a material without checking at least one or two supporting peaks.
- Ignoring overlap: multiple functional groups can contribute near the same wavenumber.
- Skipping validation when additives, blends, oxidation, or contamination may distort the spectrum.
Verification advice
When ambiguity remains, validate the hypothesis with DSC, GC-MS, or TGA, especially for blends, degraded samples, and filled polymers.
Literature behind these assignments
-
Amide confidence 1.0
“2 3 cm-1, cm-1, group peak at 1376 C-N axial deformation (amino group peak) at 1418 CH 2 (1-4)-glucosidic”
Removal of Hexavalent Chromium by Cross-Linking Chitosan and N,N’-Methylene Bis-Acrylamide DOI: 10.1007/s40710-020-00447-2 -
Alkene (C=C) confidence 1.0
“Peak at 1457 cm-1 cm-1 cm-1(stretching (C=C stretching of pyrrole rings), (N-H bending vibrations), 1376 and 1300 peaks of C=N and formation1.”
Synthesis, characterization, morphological and electrical studies of polypyrrole nanostructures DOI: 10.1063/1.5093829 -
Carboxyl (COOH) confidence 1.0
“Furthermore, the bands at 1463 and 1376 cm-1 cm-1, carboxylic acids and esters was indicated by the peak at 1735 which corresponded were attributed to the -CH2 and -CH3 bonds, respectively.”
Effects of Wet and Dry Treatments on Surface Functional Groups and Mechanical Properties of Flax Fiber Composites DOI: 10.3390/coatings13061036 -
Amide confidence 1.0
“< and 58.0% (46.9, 68.9) (P 0.01) for 1064 The 1376 the carbohydrate region was normalized with the amide I, the cm(cid:2)1 between the formalindifference in the change of peak 1376 changeswere 30.2% (24.6, 35.8) and 22.0% (11.4, 32.6) for”
Rieppo 等 - 2012 - Application of second derivative spectroscopy for DOI: 10.1016/j.joca.2012.01.010 -
Hydroxyl (O-H) confidence 1.0
“The signal 1531, 1516, and 1444 cm-1 to the cm(cid:0) 1 O-H as 1376 cm-1 was ascribed to stretching, the peak at 1224 cm(cid:0) 1 C-OH 2.3.”
Characterization of the medium infrared spectra of polyphenols of red and white wines by integrating FT IR and UV–Vis spectral data DOI: 10.1016/j.lwt.2021.111604 -
Alkene (C=C) confidence 1.0
“The C=C has a stretching vibration at 1515cm-1 853cm-1 1376cm-1 and bending vibration at [45].”
HPTLC and FTIR Fingerprinting of Olive Leaves Extracts and ATR-FTIR Characterisation of Major Flavonoids and Polyphenolics DOI: 10.3390/molecules26226892 -
Alkyl C-H confidence 1.0
“7b Absorption band Band assignment a 3340 ± 5 O-H stretching b 2892 ± 5 C-H stretching c 1645 ± 5 water bending vibrations d 1376 ± 1 C-H bending e 1002-1029 C-O at C3;”
A turning point in the bacterial nanocellulose production employing low doses of gamma radiation DOI: 10.1038/s41598-022-11010-4 -
Hydroxyl (O-H) confidence 1.0
“cm-1 Moreover, the peak band at 1376 relates to -OH bending [35,41,42].”
Fabrication and Evaluation of Water Hyacinth Cellulose-Composited Hydrogel Containing Quercetin for Topical Antibacterial Applications DOI: 10.3390/gels8120767
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